The light-shielding blades in the focal plane shutter for a camera are constructed from a plurality of arms pivotally attached to a base plate with at least one blade pivotally supported by each arm. When the arms are caused to rotate back and forth within a predetermined angular range, the blades operate between a position at which the focal plane is covered and a position of withdrawal from in front of the focal plane. The light-shielding blade constructed in this way is caused to operate through a linkage to a driving member that is attached to the base plate and rotates back and forth through a predetermined angle. Since the driving member is attached to a surface outside the blade chamber of the base plate, the base plate has a through hole formed therein, and a driving pin provided on the driving member is inserted in the through hole and is coupled to one of the above-described arms in the blade chamber. The through hole is formed as a substantially arc-like elongated hole to accommodate the back and forth motion of the driving pin centered on the rotation axis of the driving member.
Note that, besides the above-described driving member, a variety of other component members are attached to the surface of the base plate outside the blade chamber, and the majority of those are positioned relatively close to the elongated hole. Moreover, these component members are members that move during operation, or members that slide against or contact the moving members. Thus, when the shutter is operated, the sliding, contact etc. in proximity to the elongated hole results in the generation of fine wear debris.
The fine wear debris and other fine debris can enter the blade chamber through the elongated hole and become adhered to the film surface, image sensor surface, etc. Thus, the technology of Patent Document 1 has been proposed as technology to inhibit wear debris and the like from adhering to the surface of the image sensor.
A camera-use focal plane shutter described in Patent Document 1 is provided with arc-like elongated holes 1b and 1c in a base plate 1. At edges of the elongated holes 1b and 1c, walls 1f and 1g are formed so as to protrude from a surface on the opposite side to the blade chamber. Grooves 1h and 1i are formed to the outside of the walls 1f and 1g, and adhesive sheets 7 and 8 are adhered on the bottom surfaces of the grooves 1h and 1i. With such a construction, wear debris is prevented from entering the blade chamber through the elongated holes. Note that the symbols described above are those used in Patent Document 1.